Recuperator



Jun 28, 1960 G. wELLl-:NslEK RECUPERATOR 5 Sheets-Sheet 1 Filed Aug. l5, 1956 mw M RECUPERATOR 3 Sheets-Sheet 2 Filed Aug. 15, 1956 June 28, 1960 G. wELLl-:NslEK 2,942,855

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United States Patent O RECUPERATOR Gert Wellensiek, Dusseldorf, Germany, assignor to Rekuperator K.G. Dr. Ing. Schack 8; Co., Dusseldorf, Germany Filed Aug. 15, 1956, Ser. No. 604,285

Claims priority, application Germany Ang. 17, 1955 3 Claims. (Cl. 257-222) gical furnaces, asv shown and described for instance in a e British periodical Iron and Coal Trades Review, of .l anurary 22 and 29, 1952.

As seen therein, in recent years combination recuperators have been reconstructed for more amply and safely recovering the waste gas heat from soaking pits, and reverberatory furnaces, and for more highly. preheating thercombustion air delivered thereinto, which comprise a primary heat radiating steel shell compartment, and a secondary or heat convecting multitubular compartment, juxtaposed to or superimposed on the primary heat radiating compartment.

lIn a French patent specification 1,103,445, a metallic and ceramic combination recuperator is disclosed, wherein the primary shellular and the secondary tubular heat exchanger compartments are annularly nested Within each other, and wherein the hottest shell parts are noy i.e. immersed in a fusing ceramic mass, and have atixed metallic contact elements, by which the transfer of heat is to be increased.

However, it has been found meanwhile, that combination recuperators of that description are not foolproof, namely Vare still subject to be accidentally overheated, seriously damaged, melted down and completely destroyed:

These dangerous incidents occur each time, when the red or white hot steel billet, heated for rolling out or forging, is withdrawn from the furnace, and when by an oversight or accident the supply of fresh combustion air into the recuperator is not contemporarily and adequately reduced, or by failure in the automatic signalling and controlling devices of the plant.

The principal object of the invention is to provide a structurally improved steel shell tube combination recuperator, which should be more heat resistive and foolproof than prior art predecessors, namely safer against wall-bulging and other deformation troubles, as bending 'of the. tubes, breaking, leaking, melting and collapsing disasters, caused by excessive temperatures and overheati' ing beyond the resistance power of those costly chrome- `nickel steels, from which modern -recuperators are mader- A most important object of the invention-is to rightly and immediately directthe intaken cold Vcombustion air against and-aroundthe hottest and most dangerously exwhich movably' rests on and 2,942,855 Patented June 28, 1960 through a recuperator, redesigned according to this invention and shown by way of an example,

Fig. 2 is a fragmentary plan showing the recuperators upper end, wherefrom the dome is removed,

Figs. 3 and 4 are fragmentary sections on lines III- IlI and IV-IV showing baiing plates for re-directing the current of air ascending in the recuperator,

Fig. 5 is a diagram showing in perspective the paths of tlow of the ue gases and of the air through the recuperator, e Y A Fig. 6 is a front elevation in section, vertically taken through a structurally modified recuperator, shown by way of another example. Y

Fig. 7 is a section on line VII- VII in Fig. 6,

Fig. 8 is a section drawing in a larger scale on line VIII in Fig. 7Vthrough an assemblage of heat radiating and convecting tubes and rods, packed and nested in each other.

In the recuperator, redesigned according to this invention and for the purposes set forth, there areV structurally combined and cooperatively interassociated an Vupright, refractory, tubular tower, Aformed with an offset, diametrically widened base, for taking in from underneath the waste gases ascending lannular gas collecting and discharging chamber.

According to the invention means are provided inthe recuperator for splitting up or dividing the-intaken air current and redirecting its course through the recuperator, so as `to enhance its cooling effect on the heat radiating shells, and to promote the transfer of heat from the heat convecting tubes to the air.

In the recuperator embodying the invention and depicted in Figs. l-5, there is disclosed an outer refractory tower' 18, surrounding the recuperator proper and located at the refractory ilue gas inlet conduit of a furnace.

Tower 18 is closed by a refractory vaulted-dome 19,

`closes said tower 18 from thereabove.

An annular base plate 1 forms the lowermost part of the recuperator, The recuperator proper comprises an upright master steel shell or tubular element 3,: supported by said plate 1 and conducting from a rst inlet conduit 3a the slowly ascending heat radiating ilue gases from the lower end of the recuperator to the upper end of the same, and into said dome.

Numeral l2 designatesan annular foot plate or lower terminal Wall, fixed exteriorly of and to the upright tubularelement 3 at its lower part and in spaced relation 1 to the base plate 1. f

-ed at its upper end by an annularhead plate or upper Vterminalwall 4 bridging over and closing the gap between the tubular element 3 and tubular end-wall .12.

Numerals 5, 5 are spacedV apart steel tubes having upper andl lower open ends, said kopen ends being located -beyondv said terminal wall or plate 2 and terminal i posed zone ofthe heat radiating master steel shell, so as to surely prevent accidental overheating of the latter.

Various other objects, aimed at' and advantages ob- 'taine'cl by the invention will 'be recognizedhereinafter by practitioners in this eld be more fully underl'fstoodf from -the accompanying drawings, 'vvher'eint l' '-'5 rFig. lV` sv a rontelevatio section, vertically taken wall or plate 4; said tubes being suspended from the latter plate. z

Numeral `8 is an outer rst yring-shaped chamber bounded by terminal. or' foot plate 2, and joined tothe shell or tubular end wallY 12 by a ring plate 22, s''as to form said rst ring-shaped chamber around the lower part-of 'master shell or tubular element 3, and lower sections of tubes5,5'. 'Y 'Y i Numeral 7 designates inlet conduit for the airfinto lsaid rstring-shape'dfchambenwhich -is connected by ring-shaped chamber.

passageway 9 with the aforesaid hollow wal-l forming aV jupper end of the second ring-shaped chamber for dis- V charging'preheated air or like medium from the recuperator. Y

`Numerals 41, 42',- 43, 44, 45 are annular partition walls or bafiie plates with holes therein, through which the tubes `5, V extend and'with recesses c, c' (Figs. 3, 4) through which theair passes on ascending through said second As 'seen Vin Figs. 3 and 4,'and indicated in FigfS, said bafle plates have their recesses in diametrically opposed f v .positions and are spaced and in superimposed position VYupon each other, so as to form a series of annular air ducts, around the tubular Velement 3.

It is a prominentY advantageous feature of the rede- Y -Vsigned recuperator, that Ythe cold air, taken in at inlet conduit 7, is divided or bifurcated into two currents in the ring chamber 2, 8,'22, 12, and on passing Vthrough aperture or like connecting means 9 will directly impinge Yupon and .circulate around the hottest lower section 'of Y Ythe mastershell 3,'thus preventing overheating of thek latter. Y

Anp'equally important advantageous feature is, that the current of air on'ascending and passing through the recesses in the bafe plates, is repeatedly redirected, bifurcatedand rewound, so as to flow in a staggered path,

VYseen in FigaS, and always crosswise'ly impinge upon the to better suit structural local conditions ofthe plant.

The dome 19 may be fitted with an arched, self supporting refractory brick lining (not shown), so as to save a vsteel support thereunderneath. i

A reenforcing and stiffening ring 20 may be provided at the recuperators upper end. l

Structurally modified shellularv heat radiating means,

Vand multitubular heat convecting :means may be co- Vby 20' or more degrees, of the back-up'shell 8, so as operatively rearranged and associated to advantage for thepurposes of this invention, as shown Yin the recuperator, seen n Figs. 6-8.V Y-Thereingis: numeral 1', 'Y foot plate; numeral 7'.is an airiulet port in the back-up shell 8', numeral 12 is acompanion shell, numeral 9'. and numeral 29 `designate apertures in shell. y12' for thez .passage of air therethrough, numeral 10 is anfair outlet va base plate, numeral 2', a

port at the A,recuperators `upper end, numeral .6' isv a gas outlet portin` an annular gasrcha'mber 28 at. the recuperators base, numeral 22' is a ring joining the companion V'shell -12' with the back-up shell 8', numeral 18' is, a refractory tubular -towe'r formedY with an offset or diametrically widened; base. 18', numeral'19' is av refrae torydome, numeralr14 is the recuperators head plate.

, In this. cese the inner heat radiating-.master shell is.. Vmaded in .two parts, a lower section 3'\,.and, vspacedtherefrom. an Aupper section 3", by which annular gas, and all chambers are enclosed. atthe reeuperators base and upper end, numeralsr'25, 125 .are open ended -heat convecting gas tubes, which glo through the headfplate -14, being'suspended therefrom, and through the foot plate 2'.

. Numeral# 35, -35' are ended. heat radiatingV air tubes, which surround the gas tubes 25, 25', and interconnect the said air chambers, thus forming a .complete air duct therewith extending from the recuperators base to its upper end.

Also in this construction the advantage is obtained, that the recuperators hottestY-lowersection at 3' is first and directly cooled by a current of yfresh combustion air, which is split up, and subdivided, ascends through a plurality of tubular air ducts to the exitv 10', while Vthe ue gases ascending into the dome 19', are returned therefrom through Vthe gas tubes 25, 25 to the recuperators base and are discharged in amply :recooled condition through exit 6. Y Y f As seen inv Fig. 8, in the gas tubes '25', heat convecting rods 55 may be nested for cooperation therewith, by means of laps 75. l

Good results under conditions of economy and safety were obtained with recuperators redesigned, according Vto this invention, wherein thegases were recooled Yfrom 1lO0 C. to 400? C., while Ithe combustion air was heated up from normal to temperatures of 500 to 700 centigrade.

I am aware that from French Patent 1,103,445 an annularly internested arrangement of metal tubes and Vshells is known per se in another type of combination recuperators, where the hottest section of the master v shell is immersed in .a fusing Yceramic mass, and has aiiixed accessorial metallic elements; and I make no claim to that combination or arrangement,

It can thus be seen, that there has been provided in `accordance .with the inventionv a recuperator structure which has anV upright tubular element defined by a wall which has an outer surface and lan inner surface and oppositeV open ends. A first inlet conduit for a first relatively hot gaseous medium leadsinto the open end of the lower part of said tubular element, said inner surface of said wall being adapted to guide said first medium through said upright tubular element. A first outlet conduit for said first medium is located exteriorly of said wall of said tubular element and in the vicinity of said open end of the lower part of said tubular element. SaidA recuperator structure is further characterized by a first ring-shaped chamber, a second ring-shaped chamber, a second inlet conduitfor a second relatively cold gaseous medium in communication with saidrst chamber and located adjacent said open end and at -a level above said first outlet conduit for said first medium.

The aforesaid first chamber has a tubular end wall which extends Vfrom said rst .chamberV upwardly and outwardly and spaced from said wall of said tubular element to thereby define between the latter and said tubular end wall a hollow wall or a second chamber, where- Vby said outer surface of saidV tubular element forms the inner boundary of said second chamber. There are further provided means establishing connection Vbetween said rst chamber and said second chamber and located approximately at a level with Vand opposite said second inlet conduit. A plurality of tubes having upper and 'lower 'open ends are accommodated in said second lchamber and extend in spaced relation to each other and spaced from the outer surface of theit'ubular element Vand from Vvsaid tubular end wall, said second 'chamber being closed Vby upper andlower terminal walls. aforesaid upper and lower fopen ends of said tubes zare located/beyond 65- 'these Yupper and lower terminalwallsV and outside said second 'chamberfand are Vin communication withY said ltubular elementrand 'said rst outlet conduit, respectively, whereby said.V first medium upon streaming from Ysaid lower open Vend of said tubular element .through the latter is diverted into the upper 'open' ends ofsaid tubes for discharge through said: lower ope'n' ends of said tubes and thence throughsaidrst outletlconduit A second outlet conduit is furtherarrangedA in the recuperator for discharge of said 'second and vin communication with said second chamber, vsaid-seelorrd outlet conduit being located'at levelbelow the upper terminal wall of fsaidv [second clitar'nber'r,KV so that said second medium enters said iirst chafmber, thence ,streamsA through said connection means into and upwardly in said second `chamber` and inthe samedrction as said first medium when passing along the inner surface of said tubular element, said 'second medium' when lstreaming through the spaces between said tubesin'said second chamber being guided in counter direction "tothe Vstream of said first medium within saidvtubesyandout'of ,",second outlet conduit. Variousl Achanges land modifications may be made with- 'out departing fromfthe "s'piritnand` scope of the present in ,entionfand it ifsfintendedthatsuch obvious changes Vziii'd modifications be embraced by the annexed claims-` Having thus described the invention, what is claimed as new and desiredltogbe secured by Letters Patent is:

1. A recuperat'or` structure comprising an upright tubular elementhaving a lower part and an upper part, said tubular element beingdefined by a wall having an outer and inner 'surface and an open end, a first inlet conduit for a rst relatively hot gaseous medium located in the lower part of and leading into said open end of said tubular element, said inner surface of said wall being adapted to guide said rst medium from said open end in said lower part to the upper part of said upright tubular element, a first outlet conduit for said first medium from said wall of said tubular element to thereby de-V fine between the latter and said tubular end wall the said second ring shaped chamber, whereby said l outer surface of said tubular element forms the inner boundary of Ysaid second chamber, means establishing connection between said first chamber and said second chamber and located approximately at -a level with and opposi-te said second inlet conduit, a plurality of tubes having upper and lower open ends and accommodated in said second chamberand extending in spaced relation to each other and spaced outwardly from the outerV surface of the tubular element and inwardly Vfrom the inner surface of said tubular end wall, said second chamber having upper and lower terminal walls, said upper and lower ends of said tubes being located beyond vsaid upper and lower terminal walls and outside said second chamber and being in communication with said .tubular element and said first outlet conduit, respectively, whereby said first medium upon streaming from said open end through said tubular element is -diverted into the upper open ends of said tubes for discharge through said lower open ends of said tubes and thence through said first outlet conduit, and a second outlet conduit for discharge of said second medium and in communication with said second chamber, said second outlet conduit being located at a level below said upper terminal wall of said second chamber, so that said second medium enters said first chamber, thence streams through said connection means into and upwardly in said second chamber and in the same direction as said rst medium when passing along the inner surface of said tubular element, said second medium when streaming through the spaces between said tubes in said second chamber being guided in counter direction to the stream of said first medium within said tubes and out of said second outlet conduit.

l2. A recuperator operating through heat radiation and heat convection; comprising a centrally disposed upright tubular element having a lower part with a rst open end and an upper part with a second open end said tubuafer/rases lar element being defined by a wall having an outer and `an inner surface, a first inlet conduit located in the lower part of and connected to said irst open end of said tubular element for introducing fa first relatively hot gaseous medium through said tubular element along said inner surface of said wall, la first outlet conduit for said lirst medium located exteriorly of and in contact with a portion of theouter surface of `said wall of said tubular element, aY first ring-shaped chamber, a second ring-shaped chamber, a second inlet conduit Vfor a second relatively cold gaseous mediumin communication 4With said first chamber and `located above and, adjacent said first inlet said tubular end wall, a second chamber, a passageway leading from said first chamber into and establishing :communication with said secondchamber, a plurality of upright tubes accommodated in said second chamber and extending in spaced relation to each other and spaced from the outer surface of said Itubular element -and from the inner surface of said tubular end wall, said tubes ter-V mina-ting in opposite upper and lower open ends, said second chamber being defined by upper and lower terminal Walls, said upper and lower open ends of said ends of said tubes being located beyond said upper and lower terminal walls of said second chamber and being in com` munication with said second open end of said tubular element and said first outlet conduit, respectively, whereby said first medium upon streaming from said first inlet conduit through said first open end of said tubular element into the latter is first diverted from said second open end of said tubular element into the upper open ends of said tubes and thence for discharge via said lower ends of said tubes through said iirst outlet conduit, and a second outlet conduit for said second medium in communication Iwith said second chamber and located at a level below said upper terminal wall of said second chamber, so that said second medium when entering said first chamber streams through said passageway upwardly in said second chamber past said tubes therein and in the same direction as said first medium moving along said inner surface of and within said tubular element,'said first medium when entering the open upper ends of said tubes for discharge through the lower open ends of the latter via said irst outlet conduit streaming in counter direction to said second medium, which is guided through said second chamber along said ontersurface of said wall of said tubular element for discharge from said second outlet conduit, whereby said rst medium transfers its heat through radiation via the inner surface of said wall of said tubular element and then through convection via said tubes and said outer surface of said wall of said tubular element to said. second medium.

3.V A recuperator structure comprising an upright tubular element having a lower part and an upper part, said tubular element being defined by a wall having an outer and inner surface, a first inlet conduit for a iirst relatively hot gaseous medium located in said lower part of and in communication with said tubular element, said lirst medium from said rst inlet conduit being guided along said inner surface of said wall from said lower part to the upper part of said upright tubular-element, a first outlet conduit for said iirst medium located exteriorly of said wall of said tubular element and in the vicinity of said first inlet conduit, a iirst ring-shaped chamber, a second ring-shaped chamber, a second inlet conduit for a second relatively cold gaseous medium -in communication with said first chamber and located' adjacent said first inlet conduit and at a level above said rst out let conduit for said first medium, said second chamber being defined byfa space bounded by a vtubular end wall and the outer surface of said wall of said tubular element from which said tubular end wall is spaced and concentric with the latter, said second chamber being further 'determined by upperand-`lowe`r terminal walls, .said rst Achamber-being bounded by said tubular end wall, meansfestablishing connection between said first Ychar'nbe'r and said second chamber and located approximately a-t a level with .and opposite said second inlet Vconduit, a plurality of tubes accommodated in said second chamber and 'extending in spaced relation to each other and 'spaced from said outer 'surface and from the inner surface of said tubular end wall, sid tubes being open at their opposite upper and lower ends, saidY upper and lower ends ofv said tubes projecting beyond said second chamber andV being in communication 'with said tubular element and s-aid first outlet conduit, 'respectivel'y, 'a dome-Shaped member mounted above said tubular element, 'said rs't medium upon streaming from said rst inlet conduit through said vtubularelernent lbeing diverted through said dome-shaped memberinto the upper open 8 ends. of said tubes for discharge through. said llower open ends of said tubes and thence through Said rst outlet conduit, and asecofnd outlet conduit 'for said second medium in cm'nmuni'cationY with said secondchamber and positioned remote Vfrom said 4second inletconduit for said second medium, said Second medium upon entering said first chamber streaming upwardly inv said second chamber and in the Same direction as said first medium passing through said tubular element, said Afirst medium upon entering the open upper ends of said ltubes fordischarge through the lower open ends of the latter 'via said r'st outlet conduit streaming in counter direction to said second medium in saids'pac'es between said tubes located in sadsecond chamber forrdischarge from Said second outlet conduit. Y l

References Cite in the iileV of this patent y FOREIGN PATENTS A t 1,103,445 France Nov. 3, 1955 

